1. Field of the Invention
The present invention relates to a steel for a rolling part having excellent corrosion resistance, high quenching and tempering hardness, and excellent machinability for use in linear bearings, ball screws and roller bearings of industrial machinery including NC lathe, semiconductor manufacturing equipment and apparatus for office automation which must be strictly prevented from undergoing environmental contamination due to oil and grease, and further relates to a rolling part made from such steel.
2. Description of the Prior Art
A high hardness material having excellent corrosion resistance is required of the linear bearing used for NC lathe, semiconductor device and apparatus for office automation, ball screws and roller bearings used for medical apparatus and precision instruments, and martensitic stainless steel, such as SUS440C (corresponding to SAE 51440C), have hitherto been used for this purpose. However, these steels have a drawback of being poor in rolling fatigue life and machinability due to formation of a large number of coarse carbides.
By contrast, high-carbon and low-chromium bearing steels (SUJ2 series corresponding to SAE 52100 series) exhibit excellent rolling fatigue life characteristics and machinability but are poor in corrosion resistance, so that they could not be used for the above-described applications.
For the above reasons, development of a material satisfying all of the requirements for corrosion resistance, rolling fatigue life, and machinability has been strongly desired.